Alternative titles; symbols
HGNC Approved Gene Symbol: UAP1
Cytogenetic location: 1q23.3 Genomic coordinates (GRCh38) : 1:162,561,531-162,601,240 (from NCBI)
The correlation of humoral antisperm antibodies with some cases of unexplained infertility in male and female patients suggests a role for these antibodies in blocking fertilization. Diekman and Goldberg (1994) reported that antigen X (AgX) was originally identified by screening a human testis cDNA expression library with a pool of sera from male and female patients presenting at an infertility clinic. Several clinical tests determined that the individual sera contained antisperm antibodies. Diekman and Goldberg (1994) isolated cDNAs encoding 2 isoforms of AgX, designated AgX1 and AgX2, from human testis and placenta cDNA libraries, respectively. Compared with the coding sequence of AgX1, the AgX2 coding sequence contains a 48-bp insertion which encodes 16 amino acids in the C-terminal region. The authors suggested that the AgX1 and AgX2 cDNAs represent alternatively spliced AgX transcripts. Northern blot analysis detected an abundant, approximately 2.3-kb AgX transcript in testis and a slightly higher molecular mass transcript in placenta. Quantitative RT-PCR demonstrated that both AgX mRNAs were expressed in all tissues examined but at varying relative amounts. The predicted 505-amino acid AgX1 and 521-amino acid AgX2 proteins are globular and cytosolic, and contain motifs indicative of nucleotide binding. Western blot analysis using antibodies against AgX detected approximately 56- and 58-kD proteins in human testis and sperm extracts; only the 58-kD protein was found in placenta, skeletal muscle, and seminal plasma. These masses correlated well with the calculated masses of 55.5 kD and 57.3 kD for AgX1 and AgX2, respectively. Immunofluorescence analysis of human sperm localized AgX to the principal piece of the tail, the neck region of the head, and, to a lesser extent, the midpiece of the tail.
Mio et al. (1998) cloned a human UDP-N-acetylglucosamine pyrophosphorylase-1 (UAP1) cDNA and found that it was identical to the AgX1 cDNA isolated by Diekman and Goldberg (1994). UAP1 catalyzes the final step of UDP-N-acetylglucosamine (UDP-GlcNAc) biosynthesis from fructose-6-phosphate. In eukaryotes, UDP-GlcNAc is used in the GlcNAc moiety of N-linked glycosylation and the glycosylphosphatidylinositol (GPI)-anchor of cellular proteins.
Gross (2014) mapped the UAP1 gene to chromosome 1q23.3 based on an alignment of the UAP1 sequence (GenBank AB011004) with the genomic sequence (GRCh37).
Diekman, A. B., Goldberg, E. Characterization of a human antigen with sera from infertile patients. Biol. Reprod. 50: 1087-1093, 1994. [PubMed: 8025165] [Full Text: https://doi.org/10.1095/biolreprod50.5.1087]
Gross, M. B. Personal Communication. Baltimore, Md. 4/21/2014.
Mio, T., Yabe, T., Arisawa, M., Yamada-Okabe, H. The eukaryotic UDP-N-acetylglucosamine pyrophosphorylases: gene cloning, protein expression, and catalytic mechanism. J. Biol. Chem. 273: 14392-14397, 1998. [PubMed: 9603950] [Full Text: https://doi.org/10.1074/jbc.273.23.14392]